My 1TB Seagate drive not readable

I have recently bought an external Hard disk by Seagate of 1tb. Now I have a desktop as my home which has the hard disk capacity of 500 GB. The problem has started is that the moment I plug in the External disc it fails to load and do not auto run either, where as any other Capacity hard disk freely loads and auto runs by uitself. I dont understand why. Now again I run the same Disk (1TB) to other system of less capacity storage it runs smooth without any flaws, please suggest